The proposed program is designed to furnish training for two graduate level predoctoral and four postdoctoral fellows per year in reproductive biology. Trainees are expected to go on to academic investigative careers in basic science or clinical departments. The training program has been operative for the past 15 years during which time 74 postdoctoral trainees (48 M.D., 8 M.D./Ph.D.,18/Ph.D.) and 22 graduate students have received training. Trainees are selected by a five member Steering Committee following formal application to the Reproductive Endocrinology Center and, in the case of predoctoral students, to the Biomedical Sciences Graduate Program. Graduate students will pursue a course of study leading to the Ph.D. degree in Biomedical Sciences. Postdoctoral training will be offered to Ph.D. candidates in related disciplines, and also to clinically trained scientists with M.D. degrees and prior specialty training in Obstetrics and Gynecology, Pediatrics or Internal Medicine. All entering fellows will be guided by a mentoring team to determine appropriate course work, and to initiate and follow research progress. M.D. fellows with no prior graduate education will spend the first year of a 3 year fellowship attending graduate level courses and performing research. All trainees will participate in the weekly Reproductive Biology Seminar Program and Research Workshop and will take the Molecular and Cellular Reproductive Biology Course. Research training will be provided by the 16 members of the Reproductive Endocrinology Center who hold faculty positions at UCSF School of Medicine and Dentistry in both basic science and clinical departments. Current research programs address important issues in reproductive biology including: sex determination, development of the reproductive tract, biology of the ovary and testes, endocrine regulation of normal and abnormal reproductive function and genetics of infertility. The Reproductive Endocrinology Center (REC) laboratories and offices consist of approximately 13,000 square feet on two floors of the Health Sciences Instruction and Research Building. In addition a primate facility, clinical research unit and transgenic barrier facility are available for studies. Histology, hormone measurement, protein separation and sequencing, and molecular biology cores also are available for training.